Piston expander



Nov. 9, 1937. L. D. BAX 2,098,447

PISTON EXPANDER 2 sheets-sheet 1 Filed April 13, 1956 INVENT OR.

Fry 5 L/0/VL D. BAX

gawk/v ATTORNEY.

Ndv.. 9, 1937.

;.. D. BAX

PISTON EXPANDER Fild April 15, 1936 2 Sheets-Sheet 2 INVENTOR. 4/0/v4 0. BAX

BY' I #ATTORNEY.

Patented Nov. 9, 1937 I UNITED STATES "PA'I/ENT OFFICE Claims.

My invention relates to improvements in .piston expanders of the type adapted to be installed across the split in a split skirt piston.

An object of the invention is to provide means 1 for spreading the split to increase the circumference of the piston skirt.

Another object is to provide a device for this purpose that can be adjusted-manually, to control the extent of the spread.

A further object is to provide a piston skirt expander that will automatically allow the split to narrow as the heat of the piston, when in use, causes the metal therein to expand.

A still further object is to provide a device of this character, that will re-expand the-piston skirt as it cools and shrinks, back to the extent of the original manual adjustment of the expander.

Another object is to produce a piston expander that is light in weight and easily installed.

Other objects reside in the details of construction, including means 'for locking the adjustment at a predetermined degree of expansion, all of which will be more fully 'described in the course of the following description.

In the accompanying drawings in the various views of which like parts are similarly designated:

Figure 1 is a perspective view of the piston expander on a somewhat enlarged scale.

Figure 2 is a view of the expander mounted across the split in a piston, shown in an inverted position.

Figure 3 is a section taken on line 3-3, Figure 2, looking-in the direction of the arrows.

Figure 4 shows the expander in an expanded position.

Figure 5 is a section on line 55, Figure 41 Figure 6 is a section on line 6-6, Figured.

Figure 7 shows the expander allowing the split to narrow from thermal efiects.

Figure 8 is a view of the expander and a portion of the piston at the maximum temperature to which they are subjected, and

Figure 9 is an elevation showing a piston to which the expander is applied, in its normal operating position.

In the drawings, reference character l0 denotesthe expander and I2 the piston skirt in which is split I3. The expander is shaped into a central loop l4 terminating in two wings l5, each having a 0 rivet hole l6 through which rivets I? pass to 'loop I4. A screw 22, having a head 23 apertured piston is ready for service. As it heats up, durcentral portion of loop l4 and is integral therewith. Arm 3 is flanged at l9 and has a screw threaded hole at 20 in axial alinemen't and similar to another threaded hole2l in the upper bow of at 34, is operatively mounted in tapped holes 2| and 20.

At the lower end of screw 22 is a wedge member 24 in swivel relationship therewith, as shown at 30 in Figure '8. The lower end 25 of wedge 24 is v tapered and extends into a throat 26 formed be- ,tween the twoinwardly converging sides of loop 14, where they bend around to form wings IS.

A cotter key 2'! is inserted through thehole 34 in screw head 23.

The installation of the expander, in the piston, is accomplished by drilling a ho1e-in the skirt on either side of the split and riveting the wings l5 v onto the inside of the piston with the head of the screw 22-away from the piston head as shown in Figure 2. Screw 22. is then advanced toward throat 26 forcing wedge end thereinto, thus expanding loop l4 until its sides contact wings I5 and cause split l3 to widen, as shown in Figure 4. This widening of split I3 increases the circum- 25 'ference of piston skirt l2 to improve its fit in the cylinder in which it is to operate. This expansion will compensate for wear in the cylinder walls .and piston or for removal of metal from cylinder walls, to true the bore, which would otherwise cause a poor fit of the piston in the cylinder or make new oversize pistons necessary.

After the split i3 is expanded to the desired amount, cotter key 21 is put in place and the ing use, the metal in the skirt l2 will expand and force split l3 to become narrower, as the piston skirt circumference cannot exceed that of the cylinder in which' it is working; This in turn narrows throat 26 of the expander, forcing wedge end 25 out, upwardly, as seen in Figure '7. The final stage of piston expansion and split narrowing is shown in Figure 8, illustrating how tne loop M will elongate causing wedge 24 to move away from throat 26. This automatic compensation will prevent the piston becoming too tight in the cylinder which would be ruinous.

In a preferred form of the expander it will spread the split in the skirt of a piston in which it is installed about .007 of an inches the spreading wedge 24 is advanced into the throat 26 before the sides I 4 of the loop contact the wings i5. At this point of expansion, the sides normally begin to bear against the wings as shown in Figure 4 and thereby deliver more direct expansive force to the piston skirt as the spreading wedge 24 is still further advanced into thethroat 26 between the wings.

When the piston again cools, permitting the widening of the split l3, the loop I will again return to its original shape forcing wedge end 25 into throat 26 to increase the circumference of the skirt l2 and maintain an optimum fit of the piston in its cylinder.

In all the views excepting Figure 9 the expander and the piston to which it is applied, are

shown in the inverted position in which it is held for the application of the expander to -the piston prior to its insertion in the cylinder. The final adjustment of the expander is effected after insertion of the-piston in'the cylinder.

What I claim and desire to secure by Letters Patent is:

1. An expander of the character described, comprising a resilient body formed into a central loop terminating in wings projecting laterally at opposite sides of a narrowed throat, .and adapted for attachment to a piston to which the expander is applied, an arm projecting inwardly of the loop, the loop and the arm having alined apertures for the application of an adjusting screw, an adjusting screw operating in the apertures, and a wedge-member carried by the screw within the throat.

2. An expander of the character described, comprising a resilient body formed into a central loop terminating in wings projecting laterally at opposite sides of a narrowed throat, and adapted for attachment to a piston to which the expander is applied, a screw operatively mounted on the body, a wedge carried by the screw within the throat, and a pin on the screw to hold the same against rotation by contact with a piston to which the expander is attached.

3. An expander oi the character described, comprising a single strip of spring metal formed into a central loop, capable of lateral and longitudinal expansion, with its end portions bowed and terminating in wings projecting laterally at opposite sides of a narrowed throat of the loop, the wings normally being spaced from the loop and adapted for attachment to a piston to which the expander is applied to provide stops to limit lateral expansion of the loop, a screw operatively mounted in the loop, and a wedge carried by the screw within the throat.

4. An expander of the character described, comprising a strip of spring metal formed into a central loop, inclusive of a narrowed throat, fastened at its ends to opposite sides of a split of the skirt, an arm projecting inwardly of the loop, the loop and the arm having alined apertures for the application of an adjusting screw, an adjusting screw, operating in the apertures, and a wedge-member carried by the screw within the throat.

5. An expander of the character described, comprising a strip of spring metal formed into a central loop, inclusive of'a narrowed throat, fastened at its ends to opposite sides of a split of the skirt, an arm integral with the loop and projecting inwardly thereof, the loop and the arm having alined apertures for the application of an adjusting screw, an adjusting screw operating in the apertures, and a wedge-member carried by the screw within the throat.

' LIONEL D. BAX. 

